The present invention relates to an apparatus for manufacturing a magnetic recording medium, and more particularly relates to a device for manufacturing a magnetic recording medium through the oxidization of the surface of a thin magnetic film formed by ion plating, evaporative deposition or the like.
A magnetic recording medium formed of a thin film of a ferromagnetic metal directly deposited on a carrier by utilizing the methods of vacuum evaporative deposition, sputtering, ion plating or the like has recently been used to meet the demand for higher recording density in magnetic recording media. Although the magnetic recording medium of the thin ferromagnetic metal film type has a number of advantages in terms of magnetic properties, it has the disadvantages that the thin film constituting the magnetic recording layer of the medium is very likely to be oxidized and is likely to undergo exfoliation from the carrier or other damage due to contact with the recording/playback magnetic head during recording or playback. To eliminate these problems, proposals have been made to provide various protective layers on the surfaces of such thin ferromagnetic metal films.
A method of manufacturing a magnetic recording medium in which a magnetic recording layer is formed of a ferromagnetic metal such as iron, nickel and cobalt or an alloy of such metals on a plastic sheet carrier by evaporative deposition method or the like has been widely used. In accordance with one proposed apparatus, gaseous oxygen or ozone is blown against the magnetic recording layer, or the layer is exposed to an atmosphere of oxygen or ozone to oxidize the surface of the layer so as to maintain the electromagnetic converting property, durability and corrosion resistance of the medium for a long period of time. Such an apparatus is disclosed, for instance, in Japanese Unexamined Published Patent Applications Nos. 26319/83 and 63031/84, and Japanese Patent Application No. 21534/89.
In the processing methods disclosed in Japanese Unexamined Published Patent Application No. 63031/84 and Japanese Patent Application No. 21534/89, the magnetic recording layer can be oxidized immediately after being deposited on the carrier. However, the conditions for oxidization are restricted by the conditions which must be maintained for forming the layer itself. As a result, the efficiency of oxidization is very low, that is, the speed of the oxidization cannot be increased. This is a problem. Moreover, since the magnetic recording layer is exposed to ozone for the long period of 10 to 60 minutes in the processing method disclosed in Japanese Unexamined Published Patent Application No. 26319/85, the productivity of the method is so low as to not be acceptable for practical industrial use. This is also a problem.